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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Hello All,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The total size of both images is 59 kB. If
this is too big, then what¡¯s the point. I suspect that this ¡°embed images¡±
thing only works for certain software. I¡¯m using Outlook 2003 (yeah, don¡¯t
give me shit about it ¨C MS Office 2003 does things that later Office users can
only dream about).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>As a test, here¡¯s the 5 kB image I tried
to embed before:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><img width=619 height=494 id="_x0000_i1029"
src="cid:image001.gif@01D61897.A092C570"><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Pete Hartman<br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, April 21, 2020 2:29
PM<br>
<b><span style='font-weight:bold'>To:</span></b> Jimmy Moore<br>
<b><span style='font-weight:bold'>Cc:</span></b> synth-diy mailing list<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [sdiy] An Improved
Sine Shaper Circuit</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Same here Jimmy, I contacted Dave off list about it. I suspect
that perhaps they exceed the size limits that Ben described earlier this week.<br>
<br>
Pete<o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Tue, Apr 21, 2020 at 3:58 PM Jimmy Moore <<a
href="mailto:jamoore84@gmail.com" target="_blank">jamoore84@gmail.com</a>>
wrote:<o:p></o:p></span></font></p>
</div>
<blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;
margin-left:4.8pt;margin-right:0in'>
<div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Not sure if the issue is on my end, but the picture attachments aren't
rendering. Anyone else?<o:p></o:p></span></font></p>
</div>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Tue, Apr 21, 2020 at 2:29 PM David G <st1:City w:st="on"><st1:place
w:st="on">Dixon</st1:place></st1:City> <<a href="mailto:dixon@mail.ubc.ca"
target="_blank">dixon@mail.ubc.ca</a>> wrote:<o:p></o:p></span></font></p>
</div>
<blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;
margin-left:4.8pt;margin-right:0in'>
<div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>I just simulated the Thomas Henry transistor-pair sine shaper, and
compared the output to a 90-degree phase shifted pure sine wave of equal
amplitude. It is virtually impossible to tell the two apart ¨C THD = 0.57%
-- light blue is the pure one, orange is the shaped one.</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><img border=0 width=545 height=452
id="gmail-m_-6116696493604605017gmail-m_-530258260745333728gmail-m_-4674945564304717009_x005f_x0000_i1026"
src="%20"></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Here¡¯s the sine shaper circuit I¡¯m simulating ¨C this is exactly the
circuit I build into all my VCOs (transistors are 2N3904, opamp is TL07X ¨C the
11k resistors get me closer to 10Vpp than 10k):</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><img border=0 width=619 height=494
id="gmail-m_-6116696493604605017gmail-m_-530258260745333728gmail-m_-4674945564304717009_x005f_x0000_i1027"
src="%20"></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>In what way does the output of the diff pair not look like a sine
wave?</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'> </span></font><o:p></o:p></p>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center>
</span></font></div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;font-weight:
bold'>From:</span></font></b><font size=2 face=Tahoma><span style='font-size:
10.0pt;font-family:Tahoma'> Synth-diy [mailto:<a
href="mailto:synth-diy-bounces@synth-diy.org" target="_blank">synth-diy-bounces@synth-diy.org</a>]
<b><span style='font-weight:bold'>On Behalf Of </span></b>Donald Tillman<br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, April 21, 2020 12:45
PM<br>
<b><span style='font-weight:bold'>To:</span></b> Ren¨¦ Schmitz<br>
<b><span style='font-weight:bold'>Cc:</span></b> <a
href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a><br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [sdiy] An Improved
Sine Shaper Circuit</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
<div>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>On Apr 17, 2020,
at 8:53 AM, Donald Tillman <<a href="mailto:don@till.com" target="_blank">don@till.com</a>>
wrote:<o:p></o:p></span></font></p>
</div>
<div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>On Apr 17, 2020,
at 1:56 AM, Ren¨¦ Schmitz <<a href="mailto:synth@schmitzbits.de"
target="_blank">synth@schmitzbits.de</a>> wrote:<br>
<br>
Interesting circuit, and a great article.<br>
I'm pretty sure I have seen a similar technique before, because I have used it.
(cusp canceling)<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'><br>
I am very familiar with cusp cancellation. I've used it also. And
it's mentioned in the article.<br>
This is not cusp cancellation.<o:p></o:p></span></font></p>
</div>
</div>
</blockquote>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>I'd like to expand
on this for a moment...<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>I think the phrase
"cusp cancellation" has, accidentally, been misused a lot. And
that's caused confusion.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>"Cusp
cancellation" should mean that we've already got a pretty good
approximation going, but the cusps of the triangle are still coming through a
little bit. And we can cancel those by subtracting a small amount of the
original triangle wave. Sweet!<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>This would be
because the transfer curve of the diff amp pair isn't completely flat at the
top and bottom. The tanh() curve is asymptotic, so there will always be
a little slope on the peaks.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>The most common
next step is to apply negative feedback around the diff amp pair. This
could be in the form of a feedback resistor, or by adding small emitter
resistors. The negative feedback plumps up the curve and flattens the
slope at the peaks for a better overall fit. Nice!<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>But here, with the
Colin/Henry/Guest/Tillman (Have I got everybody? In order?) approach, the
output of the diff amp pair isn't remotely close to a sine wave. Not even
trying. And none of us are using negative feedback to plump out the
curve. We're not in the cusp cancelling business, we're doing something
else.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>I got here by
applying actual cusp cancellation to an actual diff amp pair with negative
feedback and a pretty good sine approximation. Then I refined it with
thousands of simulations, which lead me away from cusp cancelling, and toward
considering a compound curve of tanh(x) - ¦Âx, expressly for the bumps and the
sine shape in between. And the rest as I described.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>So I guess Dennis
Colin (ARP, Aries) got to the circuit first.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>So, I'll claim
that if a small amount of the original triangle wave is subtracted from a wave
that's roughly sinusoidal, then it's actual cusp cancellation.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'>But if the diff
amp pair contribution doesn't look like a sine wave, and there's no negative
feedback, and the transfer function can be put into the form tanh(x) - ¦Âx, then
it's this other approach that Dennis Colin pioneered.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> -- Don<o:p></o:p></span></font></p>
</div>
<div>
<div style='font-variant-caps:normal;text-align:start;word-spacing:0px'>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=1 color=black face=Menlo><span style='font-size:9.0pt;font-family:Menlo;
color:black'>--<br>
Donald Tillman, <st1:place w:st="on"><st1:City w:st="on">Palo Alto</st1:City>, <st1:State
w:st="on">California</st1:State></st1:place><br>
<a href="http://www.till.com" target="_blank">http://www.till.com</a></span></font><o:p></o:p></p>
</div>
</div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
</div>
</div>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>_______________________________________________<br>
Synth-diy mailing list<br>
<a href="mailto:Synth-diy@synth-diy.org" target="_blank">Synth-diy@synth-diy.org</a><br>
<a href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank">http://synth-diy.org/mailman/listinfo/synth-diy</a><o:p></o:p></span></font></p>
</blockquote>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>_______________________________________________<br>
Synth-diy mailing list<br>
<a href="mailto:Synth-diy@synth-diy.org" target="_blank">Synth-diy@synth-diy.org</a><br>
<a href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank">http://synth-diy.org/mailman/listinfo/synth-diy</a><o:p></o:p></span></font></p>
</blockquote>
</div>
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